Champagne flutes for wedding gift?

Going to a wedding Saturday that will probably have upwards of 200 people attending. I'm a friend of the groom. Their registry with bed bath & beyond had sets of wine glasses but no flutes! My friend and I were considering a pair of Waterford crystal champagne flutes (they cost around $150). Sound like a good idea? I know they'll use them sometime. Or do you think us and like 5 other people will get something like that? We just don't want to throw money in a card...